Slide projector



April 17, 1962 H. MuLcH SLIDE PROJECTOR 4 Sheets-Sheet 1 Filed Aug. 13,1958 INVENTOR. HA N5 M ULCH By Mm imm ATURNEYS April 17, 1962 MuLcHSLIDE PROJECTOR 4 Sheets-Sheet 2 Filed Aug. 15, 195e INVEN TOR. HANMULCH ymmm AT T RNE YS April17,1962 H. MULCH 3,029,692

SLIDE PROJECTOR Filed Aug. 13, 1958 a 4 Sheets sheet 5 F/g /a l/b l/c /Z55 /3a /3b Mii INVENToR. HA NS MULCH ATTORNEYS April 17, 1962 Filed Aug.13. 1958 H. MULCH SLIDE PROJECTOR 4 Sheets-Sheet 4 INVENTOR. HAN MULCHATTRNEYS 3,029,692 SLIDE PRGJECTOR Hans Muich, Wetzlar (Laim), Germany,assigner to Ernst `LeitztG.m.ih.'H., ptisile Werke, Wetzlar (Lahn),Germany f kFiled Aug. 13,1958, Ser. No. 754,899 Claims priority,application Germany Aug. 19, 1957 11 Claims. (Cl. StL-2S) The presentinvention relates to a ,projector `for 4slides or transparencies. Morein particular, the present invention relates to a projector for slidesor transparencies with cooling means land eleotro-mechanicfal slidechanging means. j It is known to equip projectors with cooling meansconsisting of a ventilator driven .by an electric motor. Another,separate electric motor is required as driving means for the slidechanging mechanism. It is also known to equip these projectors withremote control means.

A complete slide changing 'operation can bev performed with theseprojectors comprising the removal of a slide l'from the viewingposition, advancing of the magazine a distance equal to the spacebetween adjacent sli-des, and transferring a new slide to the viewingposition. i

lt is also possible to effect an incomplete slide changing operationwhereby only the slide is advanced to the viewing position .or isreturned to the magazine. j

According to another known construction the driving means consists of alifting magnet -instead of an electric motor.

These known constructions suffer from the disadvantage that they'require two separate driving means ,for the cooling mechanism and theslide changing mechanism, e.g. two electric motors or an, electric motorand a lifting magnet. Furthermore, the slide changing operation ef-,fected by these known projectors suffers ffrom a lack of versatilityasfthe magazine can -be moved in one direction only, usually 4in forwarddirection.

Itis therefore impossible ,to automatically show again a slide which hadalready been shown previously by remote operation, although `this isfrequently necessary and desirable.

lt `is an object of the present invention to provide `a projector withcooling meansand an `electro-mechanical,

automatic remote controlled slide changing mechanism, which has a moresimple construction and which has a greater versatility with respect tothe slide changing operation than known constructions.

It is another object of the lpresent invention to provide a projectorwith lcooling means and an electro-mechanical, automatic remotecontrolled slide changing -mechanism, having one common drivingmeansboth for `the cooling means andthe slide changing mechanism.

it is a further object of the present invention to provide a projectorwith cooling means and an electro-mechanical, lautomatic remote`controlled slide changing mechanism, which makesit possible to showagaina slide nited States Patent vide a projector with cooling means andan electro-mechanical, automatic, remote controlled slide changingmechanism, which is capable to effect both a complete slide changingoperation comprising the removal of a slide from the viewing position,advancing of the magazine a distanceequal to the space between adjacentslides, and transferring a new slide tothe viewing position, and anincomplete slide changing operation comprising only the removal of theslide from the viewing position.

It is still another object of the present inventionY to provide aprojector with cooling means and an' electromechanical, automatic,remote controlled slide changing mechanism, wherein a complete orincomplete slide changing operation can be controlled by remote controlmeans.

These objects, aswell as further objects and advantages of the presentinvention, which will become apparent as the description thereofproceeds, are achieved by the slide projector of the inventioncomprising only one motor adapted for clockwise as well ascounter-clockwise rotation and adapted to impel the ventilator as wellas the slide changing and magazine transporting means.

Preferably, the slide changing and magazine transporting means are incommunication with the motor vi freewheel clutch means. 3

The invention will be better understood upon the following detaileddescription of the accompanying drawings wherein FGURE l is across-sectional view of the projector with the cooling means and theslide changing mechanism of the present invention;

FIGURE 2v is Va perspective view of the freewheeling clutch and parts ofthe slide changing mechanism in the projector of the `present invention;

FiGURE 3 is a longitudinal sectional view of portions of the couplingand switch means for the slide changing and cooling mechanism in theprojector of the present invention;

FIGURE 4 is a top view of the'freewheel clutch and the switch andtransmission means for the cooling and slide changing mechanism in theprojector of the present invention;

FIGURE 5 is a top view of a part of the switch and transmission meansfor the cooling and slide changing `mechanism in the projector of thepresent invention;

FIGURE 6 is a wiring diagram of the electrical circuit land theprojector of the present invention.

Referring now to the drawings, more inparticular to lFIGURE 1, theprojector ofthis invention has a casing 1 tion. The clutch is so adaptedthat a coupling is effected only in a few predetermined positions of thetwo coupling discs.

The disc 10 has six recesses 11a and there are corresponding sixrecesses llc in the drivenr disc A12 with six balls 11b. At its loweredge the disc 12 bears a locking member 13 which is norm-ally in itsu-nlocked position under .the inuence of spring 13a and which ispivotable about axis 13b (see FIGU 3). The locking member 13 is adaptedto enter one or the'other of six recesses 14 in the peripheral rim ofdisc 10, according to the actual coupling position.

The disc 12 also bears a peg 1S on which is pivotally connected a lever16. Lever 16 has a slot 17a at the end opposite to the end pivotallymounted on peg 15. Into slot 17a there projects a bolt 17, which latteris mounted on a lever 19 pivotally mounted on a xed axis '18 (see FIGUREl). The end of lever 19 opposite to the end mounted on axis 18 isprovided with a slot 19a, into which projects a bolt 20a. The latter ismounted on a slide member 20. l

If disc 12 turns,vthe rotarymovement of the latter is transformed to areciprocating movement of lever 19 via lever 16 andthe bolt 17 lin slot17a of lever 16.

Via the lever end 17 and a slot 17a in said lever end 17 a lever' 19 canbe actuated which is pivotable about a xed axis/18 (see FIGURE l). Thefree end of this lever'19 actuates a slide member 20 via bolt 20a inslot 19a. VSlide member 20 can be displaced in the slideway 21thereby'bringing a slide 22 into a magazine 23 attached to the projectorcasing 1.

A cam 24 is mounted on the driven disc 12 on the same radius bearing thelocking member 13.

By means of this cam 24 a switch contact blade 2S (see FEGURE 6) can beswitched between contact 26 and contact 27.

In addition, the cam 24 actuates two switch rocker arms 28 and 29 whichare pivotally mounted at substantially their midpoints. y

The switch arm 28 has two cam followers 28a and 2817 at the ends thereofand a pivot point 28d.Y The switch arm 28 has a recess 28C (see FGURE2), which cooperates with a movable contact 30 (see FIGURE 6) Aso thatthe contact 30 can'be switched between contact 31 and contact 32.

The switch arm 29 has two cam followers 29a and 29h at the ends thereof.

The arm 29 can be pivoted upon axis 35 at its midpoint and has a recess36 actuating' a movable contact Y37 which, in turn, is engageable withstationary contacts 38 and 39.

The cam followers 28h and 29b have mounted thereon bolts 24b and 24C,respectively, projecting into the range of rotation of a nose portion24a attached projecting radially outwardly rof the disc 12.

A control segment 53 is positioned above the contact pin 50 to extend onboth sides thereof and within the range of movement of the lockingmember 13. The inner surface 54 of the control segment 53 functions as acam and has three different cam surfaces, a, b, and c. `The surfaces a,c are adapted to retain the locking member 13 in one of the recesses 14of the disc 10. In the recessed surface the locking member is allowed tofollow up the segment and is no longer retainedV by the disc 10. Betweenthe various surfaces and at the end of the surface 54e provision is madefor a slanted configuration 4in order to facilitate the scanningoperation of the locking member.

The respective lengths ofthe cam surfaces aand c are I so chosen thatthese surfaces are located within a sector a measured from the axis ofdisc 12 as a vertex--whiclh is greater than the sector enclosed by thecorrespond-ing contact points of the switch arms 28 and 29 (see FIG- UREThe last-mentioned sector is, in turn, greater than the sector 'y inwhch is subtended by each of the two c`on trol members 55 and S6 mountedupon the disc 12. The Vtwo control members are spaced vfrom each otherby the same sector as the switch arms 28 and 29.

The control member 55is pivotally positioned about axis 57 and is urgedagainst a stop 59 by a spring 5S. The control member 56 is pivotallypositioned about axis 60 and is biased against a stop 52 by spring 6I1.

Those control members 55 and 56 have guide grooves 4 Y 66 andV 67controlling the stepping gear 63 and forming together with the latter astep switching mechanism.

The stepping gear 63 is positioned on the same radian supporting thecontact pin 50 and the cam surface 54a of the control segment 53. Thestepping gear 63 is mounted on an axis 64 which is positioned in thecasing 1 of the projector and which supports another gear 65 meshing arack of the magazine 23 in a known manner. The control circuit, asillustrated in FIGURE 6 of the drawings and used in the operation of theslide projector of this invention, will next be described. The slideprojector is controlled from a remote control box 42 which comprises thefollowing controls:

43-for advancing the magazine without introducing a new slide butremoving the slide from the magazine, the magazine being movable in bothdirections.

44--for singly changing slides with the magazine moving a single step.

45-for removing the slide from the magazine without moving of themagazine.

The control circuit is energized from a source of electrical energy fromwhich extend two lines, M and N, with there being a line switch 46 inthe line M. A reversible motor 3 has a terminal 48, which is-connectedto the line N and terminals 33 and 34 which are connected to a controlcircuit to the line My which constitutes the other side of the source ofelectric energy. Either terminal 33 or 34 is connected to the power lineand the connection of these terminals determines the directionofro'tation of the motor 3..

Electrical leads extending fromlthe motor terminals 33 and 34are`connected to stationary contacts 26 and 27 respectively. There is amovable contact arm 25 engageable with 4the stationary contacts 26 and27. The movable contact arm 25 is actuated by the projection 24 on thedisc 12. The movable contact arm 25 is connected contact 44b.

The movable contact arm 44a is connected to a stationary cont-act44,.which is inturnA connected to a stationary contact 45b, whichtogether with a stationary contact 45c'is engageable with a movablecontact arm 45afwhich constitutes a control switch -for moving slidesfrom the magazine without moving of the magazine.

'Ihe movableY contact arm 45a is connected to a contact: 45, which inturn is connected to the line M; i.e., the other side of the -source ofelectric energy.

The several stationary contacts of the remote control box 42 areconnected as follows:

The stationary contact 40 is connected to the movable contact arm 30.The stationary contact 41 is connected to the movable contact arm 37.

VThe stationary contacts 3 8 and 39, which are engageable by the movablecontact'arm 37 are connected to the electrical leads extending jfrom themotor terminals 33 l and 34 respectively. r

- stationary contact 51 is connected directly to the lead extending fromthe motor terminal 33.

The stationary contact 45o is connected Awith the movable contact arm49, which is actuated by the contact pin 50and is engageable withstationary contacts 51 and 52.

The operation for changing a slide, starting when a slide is in theprojecting position is as follows:

After the main switch 46 (see FIGURE 6) has made Acontact the motorcurrent flows via the contacts 45a, 45b, 44a, lieb, 43, 47, 25, 27 andthe connecting wire represented by the dash-dotted line to the motorterminal 3d.

The motornow turns in the direction of the dash- .dotted arrow, .butclutch remains disengaged when rot-ated .in this direction in thefollowing manner:

If motor 2 turns in the direction of the dash-dotted arrow, i.e.counter-clockwise, shaft 3 and worm gear 4 .(see FIGURE 1) also turncounter-clockwise. As worm gear 4 engages the transmission gear 9, andas gear 9 meshes with gear lita mounted on disc 141, the latter is Valso,turned counter-clockwise. During such counter- .clockwise rotation ofdisc 1i), the balls 11b are free to rotate in the widened portion ofrecesses 11a in disc 1li, .and consequently no movement is transmittedto disc 12 and the latter remains stationary.

By pressing the control button 44 of the remote .control switch 4Z thecontacts 44a, c, are closed for a brief period. As la resul-t, currentis supplied to the .terminal 33 via the wire represented by the dashedline. Conseiquentiy, the polarity of the motor is reversed and the,motor now turns in the opposite, clockwise direction, `as indicated bythe dashed arrow. At this moment thedisc .12 is moved in clockwisedirection and at the very start of its rotation the cam 24 releases thespring influenced contact tongue 25, thereby closing the .contacts 25,25.

Although the contact spring 44a will return to its previous positionupon releasing the button 44, the motor continues to revolve, ,since thecontact 26 is connected to the motor terminal 33 and the circuit isclosed via the contacts 43, 47. The disc 12, which continues to beturned in the direction of the arrow (see FIGURE 6), drives the lever 16via the peg 15. The latter is connected 'via the lever 19 with the slidecarrier 2d and removes the same with the slide 22 from the viewingwindow.

In the meantime, the control member o of the disc 12 has come within therange of the stepping wheel 63 of the step switching gear. Since thespring 61 is weak compared to the lforce necessary to move .the steppingwheel 63, the control member 56 will be pivoted by the wheel 63 againstthe iniluence of the spring.

immediately thereafter the second control member 55 comes into mesh withthe stepping wheel 63 but is retained against the stop 59 by the spring58; due to the curved guide 67 the stepping wheel 63 is advanced by onestep.

The gear 65 `coupled with the stepping wheel 63 (see FIGURE `l) isdrivingly engaged with the rack of the magazine 23 to move the magazineto place the succeeding slide in position. A further rotation of disc 12releases the control member 55 from engagement with the stepping wheel63.

The lever 19 is now rpivoted in the opposite direction and a new slideis advanced to the viewing window. This movement is stopped as rsoon asthe cam 24 hits against the spring tongue 25 i.e. as soon as thedirection of rotation of the motor is reversed.

The magazine is advanced without introducing a new slide in thefollowing manner:

If one slide is still .in the viewing position (see FI"- .URES 1 and 6)the slide must first be moved back to the magazine. This is done byclosing the switch 43 against the contact '40. The motor, which has beenrunning in thedirection of therdash-'dotted arrow, is now reversed inpolarity and turns in the direction of the dashed arrow, i.e. clockwise.The shaft 3 withworm gear 4 also turns clockwise, and this movement istr-ansmitted via gear 9 and gear 10u to disc 1t), so that the latteralsoturns clockwise. During such clockwise rotation of disc the balls 11bare displaced in the narrow portion `of-recesses 11a and are clamped soas to be prevented from rolling, thereby effecting a driving engagementbetween ldiscs 1t? and 12. Consequently disc 12 also turns in clockwisedirection, and after a rotation of about 180 degrees, i.e. at a timewhere the slide has been moved back to the magazine, the locking member13 hits against the rim 54C of the control segment 53 and is held withinone of the recesses 14 thereby putting out of operation the clutch 11.

In the meantime, the contact cam.24 has touched the cam follower 29a ofthe switch arm 29, thereby actuating the same, however, without anyconsequence as the contact 4511's open.

In the same manner as described further above, the control member 56moves against the iniiuence of the spring til, whereas the secondcontrol member 55 advances the stepping wheel 63 by one step.Immediately thereafter, the cam 24 touches the cam follower 28a afterthe portion 24a has moved the switch balance into the requisite positionand the cam pivots the cam follower .Zda to actuate the spring conta-ct30 so as to close Contact 32.

As a consequence, the direction of rotation of the .motor is againreversed and the discs 1? and 12 turn in the direction .of therdash-dotted arrow. The disc 12 is lcaused to rotate .because thelockingmember 13 is still within the effective range 54a of the controlsegment 53 and eiects the coupling between discs 12 and 10 by projectinginto one of the recesses 14. During the return motion this steppingwheel `65 enters the guide way 6.7 of the control member 55, however,without being moved moving the step gear, as the control member 55 movesagainst its spring 55. After the control member has :left .the effectiverange of the stepping wheel 63, the cam v214 hits against Vthe `camfollower 2311 of the switch arm 28, thereby pivoting 'back the latter.As a result, the contacts 30, 31 are connected with each other and .thesense of rotation of the discs 1t?, V12 is again reversed.

This proce-ss is repeated as long as the contacts 40, 43 are closed andthe magazine is continuously advanced step by step.

If the magazine is desired to be moved into the opposite direction, thecontact 41 is engaged by the switch 43 instead of the contact 40. i t

In that case the switch arm 29 and the control member 56 come into play.The locking member 13 slides continuously along the cam surface 54e ofthe locking segment 53, until .the movement is interrupted byv openingthecontacts 43, 41.

By this way the disc 12 and its peg 15' execute an oscillating movement.This movement causes a small lifting of the lever 16, which however bymeans of the slot 17a in the lever 17 will not be transmitted to thelever ,19. i

It is thus possible to so control the movement of the magazine that each`slide can be projected at the desired moment and in the desiredsequence, even if it had been shown Previously.

If a slide is to be removed from the viewing position without movementof the magazine, the operation is as lfollows:

Upon switching the control switch `45 to connect stationary contact415C, the motor turns in the direction of the dashed arrow and the disc12 is driven.

The current ows through the contacts 49 `and 51. The disc L12 connectedwith the slide 20 via the elements 15 4through 19 removes the slide fromthe viewing position.

After a rota-tion of approximately l degrees, the cam f24 hits againstthe contact pin 5th and pushes the same back. Thereby ,the contact arm49 is closed against the contact 52 and the rotation of disc 12 isstopped.

lDuring `this operation the control member 56 has moved against itsspring 61 and has not actuated the stepping gear 163.

In addition, the cam 24 has pivoted the switch arm 29 without causingany `reversal `of polarity, `since its concontact 41, with the movablecontact arm 43 being locat- Ved in its initial position inengagementwith stationary contact 47. Y

In the position where the cam 24 presses against the pin t), the lockingmember I3 is located between the control cam surfaces 54a and 54b of thecontrol segment 53. This cam surface 54b of the segment 53 releases thelocking member 13 from one of the recesses 14 thereby disconnecting thediscs 1t) and 12 from each other.

The Vdisc 12 then remains in this position. If in this position theslide has to be exchanged vfor another one, the control button 44 isactuated and thereby the same movements are initiated, however, with theiirst part of the entire slide changing operation having already beencompleted.

It will be understood that this invention is susceptible to modiicationin order to adapt it to diierent usages and conditions, and,accordingly, it is desired to comprehend such modifications within thisinvention as may fall Within the scope of the appended claims.

What I claim is:

1. In a slide projector, the combinatoin of a reversible motor, coolingmeans for said projector, a magazine for slides and movable in bothdirections, means for advancing said magazine in either of said bothdirections, slide changing means for removing and returning slides toand from said magazine, and clutch means for drivingly connecting saidslide changing means and said magazine advancing means to saidreversible motor, said motor driving said slide changing means andmagazine advancing meansY as Well as said cooling means, said clutchmeans comprising a driving disc and a driven disc with said driven discbeing driven in only one direction, means comprising a linkage systemfor` interconnecting said driven disc and said slide removing andreturning means, means for drivingly interconnecting said driven discand said magazine `advancing means, said slide removing and returningmeans being operable only when said motor rotates in one of itstwodirections of rotation but said cooling -means being operable whensaid motor rotates in either direction of rotation.

i 2. In a slide projector, the combination of a reversible motor,cooling means for said projector, a magazine for slides and movable inboth directions, slide changing means for removing and returning slidesto and` from said magazine, clutch means comprising a driving discdrivingly connected to said motor and a driven disc with said drivendisc being driven in one direction, a pair of control members pivotallymonuted on said driven disc ,and having cam grooves therein, a steppingWheel engageable with said cam grooves, means for advancing saidmagazine and comprising a stepping gear. operable by said stepping wheeland drivingly connected to said magazine to move the same, and a linkagesystem drivingly interconnecting said driven disc and said slidechanging means whereby rotation of said driven disc will actuate saidslide changing means, said motor driving said slide changing means andmagazine advancing means, as well asV said Y cooling means. Y

3. In a slide projector, the combination of a reversible motor, coolingmeans for said projector, a magazine for slides and movable in bothdirections, slide changing means and comprising a stepping gear operableby said stepping Wheel and `drivingly connected to said magazine to movethe same, a linkage system drivingly interconnecting said driven discand said slide changing means whereby rotation of said driven disc willactuate said slide changing means, said motor driving said slidechanging means and magazine advancing means, as well as said coolingmeans, a pair of switch contacts in the motor control circuit forreversing the polarity of the motor, and a cam on said driven discengageable with said switch contacts for actuating the same.

4. In a slide projector, the combination of a reversible motor, coolingmeans for said projector, a magazine for slides and movable in bothdirections, slide changing means for removing and returning slides toand from said magazine, clutch means comprising a driving disc drivinglyconnected to said motor and a driven disc with said driven disc beingdriven in one direction, a pair of control members pivotally mounted onsaid driven discl and having'cam grooves therein, a stepping wheelengageable with said cam grooves, means for advancing said magazine andcomprising a stepping gear operable by said stepping wheel and drivinglyconnected to said magazine to move the same, a linkage system drivinglyinterconnecting said driven disc and said slide changing means wherebyrotation of said driven disc will actuate said slide changing means,said motor driving said slide changing means and magazine advancingmeans, as well as said cooling means, a fixed control segment having aplurality of cam surfaces vthereon spaced from the periphery of saiddriven disc, and means on said driven disc for lockingly engaging saiddriven and driving discs with said locking means being actuated by thecam surfaces on said control segment thereby enabling said magazine tobe moved in either forward or backward direction while disengaging oneof said control members from operation.

5. In a slide projector, the combination of a reversible lmotor, coolingmeans for said projector, a magazine for Y slides and movable in bothdirections,V slide changing means for removing and returning slides toand from saidmagazine, clutch means comprising a driving disc drivinglyconnected to said motor and a driven disc with said driven disc beingdriven in one direction, a pair of control members pivotally mounted onsaid driven disc and having cam grooves therein, a stepping wheelengageable with said cam grooves, means for advancing said magazineandfcomprising a steppingV gear operable by said stepping wheel anddrivingly connected to said magazine to move the same, a linkage systemdrivingly interconnecting said driven disc and said slide changing meanswhereby rotation of said driven disc will actuate said slide changingmeans, said motor driving said slide changing means and magazineadvancing means, as well as said cooling means, a fixed control segmenthaving a plurality of cam surfaces thereon spaced from the periphery ofsaid driven disc, and means on said driven disc for lockingly engagingsaid driven and driving discs with said locking means being actuated bythe cam sur- Vfaces on said control segment thereby enabling saidmagazine to be moved in either forward or backward direction whiledisengaging one of said control members from operation, there being aplurahty of recesses on the outer periphery of said driving disc toreceive said locking means, said locking means entering one of saidrecesses at a predetermined relative position of said drivingand drivendiscs thereby positioning said discs in a fixed Vpositiontrelative toeach other.

6. In a slide projector, the combination of a reversible motor, coolingmeans for said projector, a magazine for slides and movable yin bothdirections, slide changing means for removing and returning slides toand from said magazine,`clutch means comprising a driving disc drivinglyconnected to said motor and a driven disc with saidv driven discbeingdriven in only one direction, means comprising a linkage system forinterconnecting said driven disc and said slide removing and returningmeans, YYsaid slide removing and returning means being operable onlywhen said motor rotates in one of its two directions of rotation butvsaid cooling means being operable when said motor rotates in eitherdirection of rotation, a pair of lcontrol members pivotally mounted onsaid driven disc and circumferentially spaced from each other, saidcontrol membersv each Vhaving curved cam grooves therein, a steppingwheel engageable with said cam grooves, means for advancing saidmagazine and comprising a stepping gear operable by said stepping wheeland drivingly connected to said magazine to move the same, and springmeans for resiliently mounting said control members on said dri-ven-disc so that said control members can be idly moved .by engagement withsaid stepping wheel in one -direction of movement, said motor 'drivingsaid slide changing means and magazine advancing means, as well as saidcooling means.

7. In a slide projector, the combination of a reversible motor, coolingmeans for said projector, a magazine for slides and movable in bothdirections, slide changing means for removing and returning slides toand from said magazine, clutch means comprising a driving disc drivinglyconnected to said motor and a driven disc with said driven disc beingdriven in only one direction, means comprising a linkage system forinterconnecting said driven disc and said slide removing and returningmeans, said slide removing and returning means being operable only whensaid motor rotates in one of its two directions of rotation but saidcooling means being operable when said motor rotates in either directionof rotation, a pair of control members pivotally mounted on said drivendisc and circumferentially spaced from each other, said control memberseach having curved cam grooves therein, a stepping wheel engageable withsaid camA grooves, means for advancing said magazine and comprising astepping gear operable by said stepping wheel and drivingly connected tosaid magazine to move the same, said motor driving said slide changingmeans and magazine advancing means, `as well as said cooling means,spring means for resiliently mounting said control members on saiddriven disc so that said control members can be idly moved by engagementwith said stopping wheel in one direction of movement, a fixed controlsegment having a plurality of cam surfaces therein spaced from theperiphery of said driven disc, means on said driven disc for lockinglyengaging said driven and driving discs with said locking means beingactuated by said control segment, there being a plurality of recesses onsaid driving disc to receive said locking means so as to lock said discsin xed position relative to each other, said locking member projectinginto the, center cam surface of said Iiixed control segment in theposition in which said stepping gear is locked by thesaid pair ofcontrol members.

8. In a slide projector, the combination of a reversible motor, coolingmeans for said projector, a magazine for slides and movable in bothdirections, slide changing means for removing and returning slides toand from said magazine, clutch means comprising a driving disc drivinglyconnected to said motor and a driven disc with said driven disc beingdriven in one direction, Va pair of control members pivotally mounted onsaid driven disc and having cam grooves'therein, a stepping Wheelengageable with said cam grooves, means for advancing said magazine andcomprising a stepping gear operable by said stepping wheel and drivinglyconnected to said magazine to move the same, a linkage system drivinglyinter` said locking means being actuated by the cam surfaces on saidcontrol segment thereby enabling said magazine to be moved in eitherforward or backward direction while disengaging one of said controlmembers from operation, said cam surfaces comprising a central camsurface `and adjacent cam surface on both sides thereof on said controlsegrnent, the two adjacent cam surfaces each subtending an angle fromthe rational center of the driven of said control members.

9. ln a slide projector, as claimed in claim 8, with the end of saidcontrol segment disposed in the .direction of vrotation of said drivendisc when `disengaged from said clutch and the connecting portionsbetween said cam surfaces being sloped with respect-to the periphery ofthe driven disc.

10. 'In a slide projector, the combination of a reversible motor,cooling means for said projector, a magazine for slides and movable inboth directions, slide changing means for removing and returning slidesto and from said magazine, clutch means comprising a driving discdrivingly connected to said motor and a driven disc with said drivendise being driven in only one direction, means comprising a linkagesystem for interconnecting said driven disc and said slide removing andreturning means, said slide removing and returning means being operableonly when said motor rotatesin one of its two directions of rotation butsaid cooling means being operable when said motor rotates in eitherdirection of rotation, a pair of control members pivotally mounted onsaid driven disc and circumferentially spaced from each other, saidcontrol members each having curved cam grooves therein, a stepping wheelengageable with said cam grooves, means for advancing said magazine andcomprising a stepping gear operable by said stepping wheel and drivingly connected to said magazine to move the same, spring means forresiliently mounting said control members on said driven disc so thatsaid control members can be idly moved by engagement with said steppingWheel in one direction of movement, said motor driving said slidechanging means and magazine advancing means, as Well as said coolingmeans, a iixed control segment having a pluralityof cam surfaces thereinspaced from the periphery of said driven disc, means on said driven discfor lockingly engaging said driven and driving discsl with -said lockingmeans being actuated by said control segment, there being a plurality ofrecesses on said driving disc to receive said locking means so as tolock said discs in fixed position relative to each other, said lockingmember projecting into the center cam surface of said iixed controlsegment in the position in which said stepping gear is locked by thesaid pair of control members, a pair of pivotally mounted contact armswith each arm having cam followers on the ends thereof, the anglesubtended by each contact arm from the rotational center'of said drivendisc being less than the angle similarly subtended by the cam surface ofthe control segment which actuates the locking member but greater thanthe angle similarly subtended by each of said resiliently mountedcontrol members, and a cam projecting from said. driven disc andengageable with said cam followers to actuate the same.

11. In a slide projector, the combination of a reversible motor, coolingmeans for said projector, a magazine for slidestan'd movable in bothdirections, slide changing means for removing and returning slides toand from said magazine, clutch means'comprising a driving disc drivinglyconnected to said motor and a driven disc with said driven disc beingdriven in only one direction, means comprising a linkage system forinterconnecting said driven disc and said slide removing andreturningmeans, said slide removing and returning meansl being operable only whensaid motor rotates in one of its two directions of rotation but saidcooling means being operable when said motor rotates in either directionof rotation, a-'pair of control members pivotally mounted on said drivendisc and circumferentially spaced from each other, said control memberseach having curved cam grooves therein, a stepping wheel engageabie withsaid cam.

and drivingly connected to said magazine to move the same, spring meansfor resiliently mounting said control members on said driven disc sothat said control members can be idly moved by engagement with saidstepping wheel in one direction of movement, said motor driving saidslide changing means and magazine advancing means, as Well as saidcooling means, and a contact pin positioned in the path of the cammounted on said driven disc and in that area of the central cam surfaceof said xed control segment in actuating said locking member,

References Citedin the tile of this patent UNITED STATES PATENTS2,286,322 Warriner June 16, 1942 2,401,506 Pechkranz June 4, 19462,590,492 Bennett et a1. Mar. 25, 1952 2,748,653 Polian et al. .Tune 5,1956 2,874,497 Huieet ai Feb. 24, 1959

